Method and apparatus for trimming form grinder wheels



Sept. 19, 1944. w. e. GREVE METHOD AND APPARATUS FOR TRIMMING FORM GRINDER WHEELS Filed June 29, 1942 5 Sheets-Sheet 1 ul Ill-l ENTOR. WILLIAM G. GREVE.

M MMFEM ATTORNEYS Sept. 19, 1944-. w, GREVE METHOD AND APPARATUS FOR TRIMMING FORM GRINDER WHEELS Filed June 29, 1942 3 Sheets-Sheet 2 INVENTOR.

WILLIAM G. GREVE s Y E N R O T T A Sept. 19, 1944. w.' G. GREVE METHOD AND APPARATUS FOR TRIMMING FORM GRINDER WHEELS Filed June 29, 1942 5 sheets-sheet s INVENTOR. 4

' WILLIAM G.GREVE ATTORNEYS Patented Sept. 19, 1944 F ORM GRINDER WHEELS .William G. Greve, Detroit, Mich., assignorto The Gear Grinding Machine Company, Hamtr'amck, Mich., a corporation of Michigan} 'Application June 29, 1942, Serial No. 448,978

1 Claim. (01. 125-11) The invention relates to the art of form grinding and has for its object an improvement in the method of trimming the grinding surface so as to avoid certain defects therein.

In the present state of the art it is usual to provide grinding machines with trimming mechanisms which impart to the grinder wheel the desired surface contour and which restore this contour as frequently as necessary. The trimming mechanisms consist essentially of a trimming point such as a diamond and means for moving-this point through an exactly predetermined path; In case the contour is an involute or other non-arcuate curve, the direction of movementof the diamond is controlled by a templet and suitable intermediate mechanism, such as a pantograph. Itis, however,

usual to actuate the trimmer manually so that the velocity of'advancement of the trimming point corresponds to the movement of the hand of the operator. While such operation will trim the grinder to the desired contour, it has been found that the grinding surface is not always of a uniform character and this results in a corresponding lack of .uniformity in the ground surface of the work. Thus there may be microscopic lines or scratches in portions of the ground surface which are objectionable.

It is the object of the invention to avoid such defect, and to this end the invention consists, first, in an improved method of controlling the advancement of the trimming point along its path of movement. Second, in the mechanism employed for this purpose and, further, in certain features of construction as hereinafter set forth.

While my invention is applicable to various types of trimming mechanisms, I have illustrated in the accompanying drawings its application to a templet controlled pantograph mechanism.

In the drawings:

Fig. 1 is a front elevation of a pantograph trimming mechanism;

Fig. 2 is a sectional elevation illustrating the actuating means for advancing the trimming point and controlling the velocity of movement thereof, the section being partly on line 2-2,

Fig. 5 is a horizontal section on line, 5+5, Fig.2. Thepantograph mechanism is not a part ofv the instant invention and therefore a description: of thegeneral-features thereof will be sufficient.

As illustrated, A is a suitable housing or standard on which is mounted a pair of similar templet controlled pantograph mechanisms for trimming the opposite sides of a grinder wheel. Eachof these mechanisms comprises a pivotally connected parallelogram frame including a main bar B, a parallel bar C, and connecting 'cross' bars D and E. The frame is anchored on a pivot F engaging a bearing in the bar B whichis' mounted upon a carriage, G horizontally, adjustable on the frame A. Such'adjustment' may be efiected by a screw H, or other suitable means." The bars B, C, D and E arepivotally connectedto each other, and the pivotal connection between the bars B and. D includes a head I having a diamond carrier J radially adjustably secured thereto. The bar E has an extension arm'E carrying at its outer end a roller E which is adapted to engage a templet K mounted on the frame. The arrangement is such that the path of movement of the roller E on the templet K will be reproduced on a smaller scale by the path of movement of the diamond point J on the carrier J.

The pantograph trimming mechanism just de-' scribed has been heretofore used but has been manually actuated with the resulting defects in the work as above referred to. To avoid'such' defects I have provided an operating mechanismof the following construction: L is a vertically extending guideway mounted. on the rear ofthe. frame A and M is a carriage engaging said guideway to travel along the same. The carriage 'near its upper end is provided with laterally extending oross arms M and M which are connected by pivotal link bars N and N to the parallelogram frames of the two pantograph mechanisms. The lower end of the link bar N preferably pivotally engages the pivot O which connects the bars 0 and E, and this pivot is also connected to a spring P having its opposite end anchored to the frame and adapted to hold the roller E in contact with the templet K. Thus a vertical movement of the carriage M on the.

' connected with the exhaust conduit S.

on the rear wall of the housing A and including the cylinder Q and piston Q The piston rod Q after passing through a packing gland in the lowshown, a conduit S furnishes the hydraulic fluid under pressure from any suitable source and a conduit S returns the fluid to its source.

T is a valve manually operable by the handle T and adapted in one position to. connect the pressure illuid to a conduit U leading to the lower end of the cylinder Q. In the same position this valve connects the conduit U leading from the upper end of the cylinder Q to the conduit S for return of fluid. In another position on the valve the ports are reversed so that the pressure fluid is'ifadn'iitted to the conduit U and the conduit U At some point in this hydraulic system and as shown located in the conduit U, is a means for restricting the rate of flow, such for instance as a needle valve V. This may be adjusted to accurately control the velocity of movement imparted to the piston Q and through the latter, and the rod Q transmitted to the carriage M.

With the construction as described, it will be understood that the velocity of movement of the diamond trimming points is very accurately coning wheel. The velocity of advancement of the diamond points may-be varied by adjustment of the valve V, but after such adjustment will remain uniform throughout its entire movement. This precludes the leaving of any ridgesor high points in the trimmed wheel, such as frequently happens when the trimming mechanism is manually actuated. As a result, the ground surface of the work is of a uniform character in all portions thereof,

What I claim as my invention is:

A trimming mechanism for fashioning the contour of a grinder wheel comprising a pair of similar pantograph mechanisms arranged in partrimming point, an actuating arm carrying the tracing point, a templet and resilient means for holding said tracing point in contact with said templet; a casing enclosing said pantograph mechanisms, a hydraulic cylinder motor'mounted on the rear 'of said casing in a transverse plane intermediate said pantograph mechanisms and having a vertically movable downwardly extending piston rod, a vertical guideway within said casing, a slide engaging said guideway, a pin connected to said slide and passing outward through a slot in said casing and being connected at its outer end with said piston rod, a cross head mounted on said s1ide,.1inks pivotally connected to said slide andrespectively to said actuating arms,,and adjustable means for controlling the flow of fiuidto said motor to determine the velocity of movement thereof and to maintain a constant velocity of movement of said cross head and pantograph mechanisms operated thereby. WILLIAM G. GREVE. 

